1、Designation: D8027 16Standard Practice forConcentration of Select Radionuclides Using MnO2forMeasurement Purposes1This standard is issued under the fixed designation D8027; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is intended to provide a variety of ap-proaches in which manganese oxide (MnO2) can be used toconcentr
3、ate radionuclides of interest into a smaller volumecounting geometry or exclude other species that would other-wise impede subsequent chemical separation steps in an overallradiochemical method, or both.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement ar
4、e included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations p
5、rior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD7902 Terminology for Radiochemical Analyses3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer toTerminologies D1129 and D7902.4. Summary of Practice4.1 These practices de
6、scribe different processes throughwhich MnO2can be used to concentrate specific radionuclidesof interest into a smaller volume counting geometry or excludeother species that would otherwise impede subsequent chemi-cal separation steps in an overall radiochemical method, orboth.4.2 Published studies
7、(1-5)3have addressed in detail thevarious manners in which hydrous manganese dioxides can besynthesized and the variety of crystal forms of hydrousmanganese dioxide that can result. The literature describes thefollowing general categories in which hydrous manganesedioxide can be prepared.4.2.1 Guyar
8、d Reaction:3Mn2112MnO412H2O5MnO214H14.2.2 By the reduction of permanganate with reducingreagents such as hydrogen peroxide (H2O2) or hydrogenchloride (HCl).4.2.3 By the oxidation of Mn(II) salt under alkaline condi-tions with oxidizing reagents such as potassium chlorate(KClO3), H2O2, ozone (O3), or
9、 ammonium persulfate(NH4)2S2O8).4.3 The presented practices are not meant to address everypossible approach to the generation and use of MnO2but aremeant to present some more typical practices that may begenerally useful.5. Significance and Use5.1 This practice is applicable to the separation of spe
10、cificradionuclides of interest as part of overall radiochemicalanalytical methods. Radionuclides of interest may need to bequantified at activity levels of less than 1 Bq. This may requiremeasurement of less than 1 fg of analyte in a sample which hasa mass of a gram to more than several kilograms. T
11、his requiresconcentration of radionuclides into a smaller volume countinggeometry or exclusion of species which would impede subse-quent chemical separations, or both. MnO2has shown goodselectivity in being able to concentrate the following elements:actinium (Ac), bismuth (Bi), lead (Pb), polonium (
12、Po), pluto-nium (Pu), radium (Ra), thorium (Th), and uranium (U) asnoted in the referenced literature (see Sections 4 and 8). TheMnO2can be loaded onto a variety of substrates in preparationfor use or generated in-situ in an aqueous solution. Thepresented processes are not meant to be all encompassi
13、ng ofwhat is possible or meant to address all limitations of usingMnO2. Some limitations are noted in Section 6, Interferences.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current ed
14、ition approved Feb. 15, 2016. Published May 2016. DOI: 10.1520/D8027-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe AS
15、TM website.3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Interferences6.1 MnO2is able to achieve a very good decontaminationfactor from
16、 monovalent cations in solution as evidenced by 8.3below in which it is used in seawater. However, in the case ofelevated concentrations of divalent cations, for examplebarium, the recovery of analytes of interest can be significantlyreduced (6). Additionally in the case of seawater, the recoveryof
17、analytes such as uranium may also be substantially reduced.In such cases the use of an isotopic tracer can be very importantto correct for such reduced recovery. The MnO2separation isalso very conducive to being easily repeated to achieve asecond stage of separation from potentially interfering spec
18、ies.7. Reagens7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Ot
19、her grades may beused, provided that the reagent is of sufficiently high purity topermit its use without increasing the background of themeasurement.7.1.1 Some reagents, even those of high purity, may containnaturally occurring radioactivity, such as isotopes of uranium,radium, actinium, thorium, ra
20、re earths and potassium com-pounds or artificially produced radionuclides, or both.Consequently, when such reagents are used in the analysis oflow-radioactivity samples, the activity of the reagents shall bedetermined under analytical conditions that are identical tothose used for the sample. The ac
21、tivity contributed by thereagents may be considered to be a component of backgroundand applied as a correction when calculating the test sampleresult. This increased background reduces the sensitivity of themeasurement.7.2 Ammonium hydroxide, 15 M NH4OH, (concentratedreagent).7.3 Ammonium hydroxide,
22、6MNH4OHAdd 400 mL ofconcentrated ammonium hydroxide to 400 mL water. Dilute to1 L with water and mix well.7.4 Bromocresol purple pH indicatorAdd 0.1 g bromo-cresol purple in 18.5 mL of 0.01 M sodium hydroxide (NaOH)solution. Dilute to 250 mL with water and mix well.7.5 Hydrogen peroxide, 30 % H2O2.7
23、.6 Iron chloride, FeCl3.7.7 Potassium permanganate, KMnO4.7.8 Potassium permanganate, 0.5 M KMnO4Add 79 g ofKMnO4to 750 mL water. Dilute to 1 L with water and mixwell.7.9 Sodium hydroxide, 0.01 M NaOHAdd 0.1 g NaOH to250 mL water.8. Procedure8.1 Use of MnO2Generated in-situ to Pre-ConcentrateSample
24、Analytes:8.1.1 The precipitation of MnO2from a water sample maybe most conveniently performed on a volume of 0.1 to 2 L butlarger volumes are possible (7 and 8). Any isotopic tracersshould be added and the valence states of the tracers andanalyte species allowed to equilibrate before proceeding.8.1.
25、2 Add to the water sample approximately 10 mg ofKMnO4and allow to dissolve. Optionally, approximately 2 mgof FeCl3may also be added to improve the obtainableseparation factor.8.1.3 The pH indicator bromocresol purple may be added tothe water sample to provide a color indicator in the followingstep o
26、f raising the pH.8.1.4 Add to the water sample approximately 1 mL of about30%H2O2.8.1.5 The precipitation step to follow is best performed atambient temperature if a period of one or more days isavailable to allow for complete settling and development of theprecipitate. Alternatively the promptness
27、of the precipitationcan be assisted by gently heating the water sample, for exampleto approximately 7080C.8.1.6 Add sufficient 6 M NH4OH to the water sample toraise the pH to about 8. If bromocresol purple was added in theprior step this pH would be indicated by a color change topurple. The needed p
28、H change could also be measured throughuse of pH test strip or pH meter.8.1.7 Following complete development and settling of theprecipitate the supernate may be removed by aspiration orcareful decantation. The small amount of MnO2precipitatemay be optimally isolated into a small pellet by transferri
29、ng thebottom layer containing the precipitate (about 50 mL) to acentrifuge tube and centrifuging. The precipitate may befurther washed up to two times with water and centrifugationrepeated.8.1.8 An alternative to centrifugation is filtration through a0.45 m filter but may require more time to accomp
30、lish thefiltration in a careful manner.NOTE 1Asimilar procedure can be used on acid leachates of sedimentsamples but care should be taken when adding6MNH4OH to strong acidsolutions.8.1.9 The washed MnO2precipitate and the incorporatedanalytes of interest and associated isotopic tracers may betaken t
31、hrough further separative steps, for example extractionchromatography, or may be transferred to a suitable countinggeometry.8.2 Use of MnO2Impregnated Resin Beads:8.2.1 Atypical radiochemical separation geometry is the useof a column into which an aqueous sample can be poured andexcellent contact ma
32、de with a supported extraction media.MnO2has also been found to be quite amenable to thisapproach (9-13). MnO2loaded resin can be made or purchasedcommercially for use in such column geometry. This approachallows the amount of MnO2loaded resin to be readily adjusted4Reagent Chemicals, American Chemi
33、cal Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pha
34、rmacopeial Convention, Inc. (USPC), Rockville,MD.D8027 162to the sample aqueous volume and expected analyte concen-tration. As well the retained analytes can also be readily elutedfrom the supported media using the same column geometry.8.3 Use of MnO2Impregnated Polymer Fibers/Cartridges:8.3.1 The n
35、aturally occurring alpha-emitting radium iso-topes223Ra,224Ra, and226Ra as well as beta-emitting228Rahave been extensively used as geochemical tracers in studies oflarge water bodies primarily seawater but fresh water as well.Such studies rely on the large variation in half-lives of thoseradium isot
36、opes from a few days to more than a thousandyears to characterize the sources of those radium isotopes andtheir mixing in large water bodies.8.3.2 While the abundance of these radium isotopes on anabsolute basis and relative to each other can provide usefulinformation the concentration of these radi
37、um isotopes in largewater bodies, especially in seawater, can be quite low andpresents a challenge in measurement with needed precision.The geometry of MnO2impregnated on polymer fibers/cartridges provides a high surface area that when contactedwith a large volume of water (tens, several hundred, ev
38、enseveral thousand litres) allows a representative sampling of thecontained radium in a convenient manner (14-25). This contactwith the MnO2impregnated polymer fibers/cartridges can beaccomplished in-situ or using a collected and contained largevolume water sample. Controlled studies have shown that
39、 theradium extraction efficiency is high but not may not be 100 %so where an absolute radium isotope concentration is needed agrab sample of sufficient volume may need to be taken for fixedlaboratory analysis. However, such grab sample radium isotoperesults may be combined with relative radium isoto
40、pic resultsto provide an overall useful set of radium isotope data.8.3.3 The typical manner of impregnating the fiber/cartridgemedia with MnO2is to immerse in a similar volume of 0.5 Mpotassium permanganate solution at 70 to 80C for 10 minutes.The reaction is exothermic and after the few minute cont
41、act theimpregnated material should be transferred to deionized waterfor washing after which it may be dried and stored pending use.8.3.4 After contact with the water being characterized forradium isotope content there are a variety of manners in whichthe radium content can be measured. These include
42、 gammaspectrometry of the dried fiber/cartridge in a standardgeometry, measurement of the radon decay progeny from aircirculated through the dried fiber/cartridge, or elution of theradium from the fiber/cartridge media.8.4 Use of MnO2Impregnated Thin Film:8.4.1 While the approaches in the prior two
43、sections madeuse of the associated high surface area of the substrate tomaximize the advantage of the impregnated MnO2such asubstrate geometry is not necessary where the aqueous samplevolume is reasonably small and a longer contact time can beused. In this situation a thin polymer disc substrate geo
44、metrythat can then be used for alpha spectrometry counting hasnotable value (26-29).8.4.2 The thickness of the deposited MnO2can be on theorder of 1 micrometer which still allows good alpha energyresolution to be obtained. The thickness of the deposited MnO2can be controlled through the deposition t
45、ime but there may bea tradeoff with analyte recovery. The cited published work onthis approach uses aqueous sample volumes of about 1 L anda contact time of up to 2 days.9. Keywords9.1 chemical separation; concentration; hydrous manganeseoxide; manganese oxide; pre-concentrationREFERENCES(1) Tsuji,
46、M.,and Mitsuo, A. Synthetic Inorganic Ion-Exchange MaterialsXXXVI. Synthesis of Cryptomelane-Type Hydrous Manganese Diox-ide as an Ion-Exchange Material and Their Ion Exchange SelectivitiesTowardsAlkali andAlkaline Earth Metal Ions, Solvent Extraction andIon Exchange, Vol 2, No. 2, 1984, pp. 253274.
47、(2) Shuckrow, A. J., The Removal of Radionuclides from AqueousSolution by Hydrous Manganese and Co-formed Manganese-IronOxides, PhD dissertation, Rensselaer Polytechnic Institute, Ann Ar-bor: University Microfilms, Inc., 1967.(3) Schuman, R. P., Radiochemistry of Manganese, National Academy ofScienc
48、es Subcommittee on Radiochemistry, NAS-NS-3018 (Rev.),1971, pp. 1314.(4) Vesely, V., and Pekarek, V., Synthetic Inorganic Ion-Exchangers I.Hydrous Oxides and Acidic Salts of Multivalent Metals, Talanta,Vol19, 1972, pp. 219262.(5) GMELIN Handbook of Inorganic and Organometallic Chemistry,Manganese, T
49、eil C1, 1973, pp. 126156.(6) Nelson, A. W., May, D., Knight, A. W., Eitrheim, E. S., Mehrhoff, M.,Shannon II, R., Litman, R., and Schultz, M. K., Matrix Complicationsin the Determination of Radium Levels in Hydraulic FracturingFlowback Water from Marcellus Shale, Environmental Science andTechnology Letters, Vol 1, No. 3, 2014, pp. 204208.(7) Bojanowski, R., Radecki, Z., and Burns, K., Determination of radiumand uranium isotopes in natural waters by sorption on hydrousmanganese dioxide followed by alpha-spectrometry, Journal of Ra-dioanalytical and Nuclear Chem
